This proposal describes progress towards analyzing the mechanism of L-proline and D-glucose triggered germination of Bacillus megaterium QM B1551 spores. For both trigger reagents, only a brief exposure of spores to the reagent is necessary to trigger germination and then initiation of germination can continue in their absence. No detechtable uptake was observed during the time of triggering. With the use of L-proline chloromethyl ketone, a set of proteins in spore membranes was identified that may be involved in triggering. Also, with acetic anhydride modification of spore proteins in vivo, a set of proteins was identified that co-purify with one mentioned above. Thus by two procedures, it may be possible to identify the proline trigger site. In addition, in vitro studies with spore membranes have begun using electron spin resonance and fluorescent probes. By both techniques, L-proline was shown to cause some biophysical change in the membranes. The mechanism of D-glucose triggering is being analyzed similarly. Therefore these techniques may be used to investigate how L-proline interacts with spore membranes and may lead to an understanding of the in vivo reactions for triggering germination.